1. Field of the Invention
The present invention relates to a positive, high heat-resistant photosensitive resin composition usable for surface protective film and interlayer insulating film in semiconductor devices and for interlayer insulating film in display devices, to a production method for a heat-resistant, cured relief pattern using the positive, high heat-resistant photosensitive resin composition, and to a semiconductor device containing the relief pattern.
2. Description of the Related Art
For surface protective film and interlayer insulating film in semiconductor devices, used is polyimide resin that has excellent heat resistance, electric properties and mechanical properties. The polyimide resin is, at present, supplied generally as a photosensitive polyimide precursor composition; and this is applied onto a support, and then patterned, developed and processed for thermal imidation, thereby readily forming a surface protective film, an interlayer insulating film or the like in a semiconductor device; and the composition is characterized in that the process with it may be greatly shortened as compared with a conventional non-photosensitive polyimide precursor composition.
However, the photosensitive polyimide precursor composition requires a large quantity of an organic solvent such as N-methyl-2-pyrrolidone as the developer in the development step, and in view of the recent increase in environmental problems, an organic solvent-free method is desired. Given that situation, recently, various proposals of a heat-resistant photosensitive resin material developable with an aqueous alkali solution like photoresist have been made.
Above all, recently, a method of using a PBO precursor composition, which is prepared by mixing an aqueous alkali solution-soluble hydroxypolyamide, such as polybenzoxazole (PBO) precursor with an optically-active ingredient such as a photosensitive diazoquinone compound, as a positive photosensitive resin composition has come to attract special attention.
The development mechanism of the positive photosensitive resin is as follows: A non-exposed photosensitive diazoquinone compound is insoluble in an aqueous alkali solution, but after exposed to light, the photosensitive diazoquinone compound undergoes chemical change to be an indenecarboxylic acid compound and becomes soluble in an aqueous alkali solution. Based on the dissolution speed difference between the exposed part and the non-exposed part, only the non-exposed part may form a relief pattern (for example, see JP-A-56-27140).
On the other hand, as a technique of separating the photosensitivity from the insoluble function of the non-exposed part, in the field of semiconductor photoresists, much employed is a chemical amplification-type photosensitive composition of such that it generates a catalytic amount of an acid through exposure to light, and then in the subsequent heating process, the alkali-insoluble group in the composition is converted into an alkali-soluble group through chemical reaction with the acid having been generated through the photoexposure and acting as a catalyst. Also in the technical field of the present invention, such a chemical amplification-type photosensitive composition is disclosed (for example, see JP-T-2002-526793).
However, with the recent development of semiconductor technology, finer pattern fabrication is required and it is also required to lower the curing temperature after patterning.
In particular, when the curing temperature is lowered, it is known that thermal benzoxazole cyclization is hardly promoted. Regarding this problem, for example, it has already been reported that the problem could be solved by addition of sulfonic acid or a sulfate compound (for example see JP-A-2006-010781 and JP-A-2006-126809). However, it has been known that even these compounds are still insufficient.
Specifically, a material having excellent lithography performance (film retentiveness, resolution performance), capable of curing at a low temperature not higher than 250° C. and having heat resistance has not as yet been found out.